KR20000068535A - High strength flexible film package - Google Patents

Abstract

The present invention provides a product such as a bag 10, a pouch, a case, or a sheet formed by bonding a film fragment including a non-cross-laminated film. The product has a parallel plate burst strength of at least 300 inches of water, more preferably about 300 to 2000 inches of water. The film comprises one of a wide range of polymers, with linear low density polyethylene being preferred. The film is either heat sealed on its own or is melted on another film (preferably similar or identical film) Preferably, the total thickness of the film is about 3 to 20 mils. This is surprising given the non-lamination.

Description

High Strength Flexible Film Packaging Material {HIGH STRENGTH FLEXIBLE FILM PACKAGE}

There are a wide range of products that can be beneficial by being packaged in high strength flexible film packaging, ie flexible film packaging having high tear resistance, high burst strength and / or other desirable features of high strength packaging. High-strength packaging can avoid packaging perforation, tearing, damaged seals, and the like. In addition, these high strength flexible film packaging materials are rarely discarded due to the relatively low amount of materials used in the packaging, so wood crate, which is the most common packaging form requiring high strength, abuse-resistant packaging, Less impact on the environment (and easier to recycle) than bulky alternatives such as paper products (eg corrugated paper products), foams and the like. The light weight and small volume of these high strength flexible film packaging materials also provide significant transportation advantages over larger volumes of the packaging materials while making packaging and the like difficult to handle. In addition, such high strength flexible film packaging products that are not reinforced with non-thermoplastic materials are more easily recycled (e.g., easier than glass fiber reinforced plastic film packaging).

One high strength flexible film packaging material that has been in use for some time is the VALERON® strength film sold by Van Leer Flexibles, Inc. of Houston, Texas. Valeron strength films are made from high density stretched and cross-laminated polyethylene and are said to be puncture resistant, tear resistant and chemical resistant. Valeron-strength films are also strong, are smooth in surface, exhibit balanced tear resistance, are uniform in thickness, printable with solvent-based inks and water-based inks, and can be laminated to paper, films, and other substrates. Valeron-strength film also retains its properties in harsh environments, has an operating temperature range of -70 ° F to 200 ° F and more, and is useful in the flexible packaging, transportation, construction, agriculture, photo and tag & label industries. It is said. Valeron strength films are said to have the same overall thickness and much better tear resistance than single-layer films made of the same polymer biaxially stretched. Valeron strength films are also said to be improved over other cross-laminated films because they are annealed (ie applied at high temperatures of 35 ° C. to the lowest melting point of the thermoplastic material except the adhesive or bonding layers). The annealing process reportedly allows the valence strength film to exhibit greater impact strength compared to the corresponding binned film.

However, valeron strength films are expensive compared to other films. This high cost is obviously due to the costs associated with cross-laminaion and annealing. It may be desirable to provide high strength flexible film packaging that has performance characteristics equivalent to valence strength films but is less complex to manufacture.

Summary of the Invention

The present invention relates to a high strength flexible film packaging material having features equivalent to the packaging material formed from the cross-laminated film described above, but which is substantially less complex to manufacture. Surprisingly, it is possible to seal an uncrosslaminated film of equal thickness to a valerian strength film to form a packaging material that is very resistant to impact and rupture, i.e., having a parallel plate burst strength of at least 300 inches of water. Found. This high burst strength is surprising in that the film is not cross-laminated and even essentially unannealed. Another unexpected result is that this significant burst strength is obtained at a thickness nearly equal to the total thickness of the crosslaminated annealed film. Thus, the film is simple and relatively inexpensive to manufacture, while providing a burst strength equivalent to that of a more complicated and expensive cross-laminated annealed package. In addition, surprisingly the packaging according to the invention can use polyethylene copolymers, which is substantially comparable to the chemical resistance, operating temperature range and printability associated with crosslaminated annealed flexible films.

As a first aspect, the present invention relates to an article comprising an uncrosslaminated film. Uncrosslinked films include linear low density polyethylene, high density polyethylene, homogeneous ethylene / alpha-olefin copolymers, polycarbonates, polyester homopolymers, polyamides, ethylene / acid copolymers, ethylene / ester copolymers, ethylene / vinyl acetate aerials At least one selected from the group consisting of copolymers, ionomers, ethylene / carbon monoxide, very low density polyethylene, low density polyethylene, polyolefins, ethylene / propylene copolymers, ethylene / norbornene copolymers and ethylene / styrene copolymers. Uncrosslinked films may be sealed on their own or linear low density polyethylene, high density polyethylene, homogeneous ethylene / alpha-olefin copolymers, polycarbonates, polyesters, polyamides, ethylene / acid copolymers, ethylene / ester copolymers, Ethylene / vinyl acetate copolymers, ionomers, ethylene / carbon monoxide, very low density polyethylene, low density polyethylene, polyolefins, ethylene / propylene copolymers, ethylene / propylene / diene terpolymers, ethylene / norbornene copolymers and ethylene / styrene It is sealed to another film comprising at least one member selected from the group consisting of copolymers. (Preferably, the film comprises LLDPE, more preferably at least one layer comprising at least 80% by weight of LLDPE, based on the weight of the layer comprising LLDPE, even more preferably the film A blend of LLDPE and EVA, and even more preferably, a blend of about 80-95 weight percent LLDPE, 5-19 weight percent EVA and 1-5 weight percent antiblock masterbatch.) This product has a parallel plate burst strength of 300 inches or more of water. Preferably, the total thickness of the film is about 3 to 20 mils and the article has a parallel plate burst strength of about 300 to 2000 inches of water. The film may be a single layer film or a multilayer film.

Optionally or optionally, the film may further comprise a crosslinking layer comprising a polymeric crosslinker, wherein the polymeric crosslinker comprises a reaction product of a polyene monomer and a C ₃ -C ₈ olefin monomer. . Optionally, a third monomer other than the C ₃ -C ₈ olefin monomer can also be included in the polymeric crosslinking enhancer. The third monomer may be an olefin monomer, styrene or styrene derivative, cycloolefin (e.g. norbornene), unsaturated esters (e.g. vinyl acetate, methyl acrylate, ethyl acrylate and butyl acrylate), acid (e.g. acrylic acid or meta Acrylic acid) and acid salts. Polymeric crosslinking enhancers may optionally be blended with other polymers. Alternatively, the polymer may be used alone. More specifically, polymeric crosslinking enhancers include ethylene / propylene / ENB terpolymers, ethylene / hexene / ENB terpolymers, ethylene / octene / ENB terpolymers, ethylene / hexene / 5-vinylnorbornene terpolymers and And at least one member selected from the group consisting of ethylene / octene / 5-vinylnorbornene terpolymers.

Preferred multilayer films comprise a first inner layer and a second inner layer, the inner layers each being an ethylene / vinyl ester copolymer, an ethylene / vinyl acid copolymer, an ionomer and a homogeneous ethylene / density having a density of about 0.87 to 0.91 g / cc. At least one selected from the group consisting of alpha-olefin copolymers, more preferably the ethylene / vinyl ester copolymer is at least one selected from the group consisting of ethylene / methyl acrylate copolymers and ethylene / vinyl acetate copolymers Wherein the ethylene / vinyl acid copolymer comprises an ethylene / methacrylic acid copolymer. Preferred multilayer films further comprise a first outer layer and a second outer layer, the outer layers each comprising: (a) linear low density polyethylene, high density polyethylene, low density polyethylene, very low density polyethylene, homogeneous ethylene / alpha-olefin copolymer , Olefin homopolymer, polycarbonate, polyamide, ethylene / acid copolymer, ethylene / ester copolymer, ester homopolymer, ionomer, ethylene / carbon monoxide copolymer, ethylene / propylene / diene terpolymer, ethylene / norbornene air At least one selected from the group consisting of copolymers and ethylene / styrene copolymers; And (b) at least one selected from the group consisting of ethylene / vinyl ester copolymers, ethylene / vinyl acid copolymers, ionomers and homogeneous ethylene / alpha-olefin copolymers having a density of about 0.87 to 0.91 g / cc. At least one layer selected from the group consisting of a first outer layer and a second outer layer is sealed on itself or on another outer layer. Preferably, the total thickness of the multilayer film is about 3-7 mils, the product has a parallel plate burst strength of about 300-1000 inches of water, more preferably the total thickness is about 4-5 mils, water about 400 Parallel plate burst strength from 700 inches to 700 inches.

The film may or may not be heat shrinkable. If the film is heat shrinkable, the film is preferably biaxially stretched and the free shrinkage at 185 ° F. is about 10-100%.

The film is at least one selected from the group consisting of ethylene / vinyl alcohol copolymers, polyvinyl chloride, polyvinylidene chloride, polyamide, polyester, polyacrylonitrile; More preferably further comprises an O ₂ -blocking layer comprising at least one selected from the group consisting of ethylene / vinyl alcohol copolymers, polyvinyl chloride, polyvinylidene chloride, polyamides, polyesters and polyacrylonitriles can do.

Preferably, the film is irradiated at a radiation dose of about 50 to 150 kGy, more preferably about 75 to 125 kGy, even more preferably about 90 to 110 kGy, even more preferably about 100 kGy.

The product of the invention preferably comprises at least one selected from the group consisting of end-seal bags, side-seal bags, L-shaped sealed bags, pouches and backseamed cases. do.

As a second aspect, the invention relates to a particularly preferred product according to the invention, wherein the product comprises a first multilayer film and a second multilayer film, wherein the first multilayer film is not a cross-laminated film, but is a second multilayer The film is also not a cross-laminated film, the first multilayer film is sealed to the second multilayer film, the thickness of the first multilayer film is about 3 to 20 mils, the thickness of the second multilayer film is about 3 to 20 mils, The product has a parallel plate burst strength of about 300 to 2000 inches of water. Preferably, the first multilayer film comprises linear low density polyethylene, high density polyethylene, low density polyethylene, very low density polyethylene, homogeneous ethylene / alpha-olefin copolymers, olefin homopolymers, polycarbonates, polyamides, ethylene / acid copolymers, At least one selected from the group consisting of ethylene / ester copolymers, ester homopolymers, ionomers, ethylene / carbon monoxide copolymers, ethylene / propylene / diene terpolymers, ethylene / norbornene copolymers and ethylene / styrene copolymers do. Preferably, the second multilayer film comprises linear low density polyethylene, high density polyethylene, low density polyethylene, very low density polyethylene, homogeneous ethylene / alpha-olefin copolymers, olefin homopolymers, polycarbonates, polyamides, ethylene / acid copolymers, At least one selected from the group consisting of ethylene / ester copolymers, ester homopolymers, ionomers, ethylene / carbon monoxide copolymers, ethylene / propylene / diene terpolymers, ethylene / norbornene copolymers and ethylene / styrene copolymers do.

Preferably, the first multilayer film comprises a first inner layer, a second inner layer, a first outer layer and a second outer layer. Preferably, the inner layers are each at least one selected from the group consisting of ethylene / vinyl ester copolymers, ethylene / vinyl acid copolymers, ionomers and homogeneous ethylene / alpha-olefin copolymers having a density of about 0.87 to 0.91 g / cc. It includes. Preferably, the outer layers are each (a) linear low density polyethylene, high density polyethylene, low density polyethylene, very low density polyethylene, homogeneous ethylene / alpha-olefin copolymer, olefin homopolymer, polycarbonate, polyamide, ethylene / acid air At least one selected from the group consisting of copolymers, ethylene / ester copolymers, ester homopolymers, ionomers, ethylene / carbon monoxide copolymers, ethylene / propylene / diene terpolymers, ethylene / norbornene copolymers and ethylene / styrene copolymers ; And (b) at least one selected from the group consisting of ethylene / vinyl ester copolymers, ethylene / vinyl acid copolymers, ionomers and homogeneous ethylene / alpha-olefin copolymers having a density of about 0.87 to 0.91 g / cc. Preferably, the second multilayer film comprises a first inner layer and a second inner layer and a first outer layer and a second outer layer, the inner and outer layers being combined with the inner and outer layers of the first multilayer film. Matches. In the present product, at least one layer selected from the group consisting of a first outer layer of the first multilayer film and a second outer layer of the first multilayer film is a first outer layer of the second multilayer film and a second outer layer of the second multilayer film. Sealed to one or more layers selected from the group consisting of layers. Preferred film thicknesses, parallel plate burst strengths, dosages, etc., are consistent with the product according to the first aspect of the invention.

Preferably, the two outer layers of the first multilayer film are substantially the same in chemical composition and thickness, the two inner layers of the first multilayer film are substantially the same in chemical composition and thickness, and the two of the second multilayer film The outer layer is substantially identical in chemical composition and thickness, and the two inner layers of the second multilayer film are substantially identical in chemical composition and thickness. Preferably, the first multilayer film is substantially the same as the second multilayer film in chemical composition and thickness. Preferably, the two outer layers of the first multilayer film are substantially the same in chemical composition and thickness, the two inner layers of the first multilayer film are substantially the same in chemical composition and thickness, and the two of the second multilayer film The outer layer is substantially identical in chemical composition and thickness, and the two inner layers of the second multilayer film are substantially identical in chemical composition and thickness.

Preferably, the product comprises at least one selected from the group consisting of a pouch and a butt-sealed back seamed case with butt-seal tape.

Optionally and in some applications, preferably, the first multilayer film comprises at least one member selected from the group consisting of ethylene / vinyl alcohol copolymers, polyvinyl chlorides, polyvinylidene chlorides, polyamides, polyesters, polyacrylonitriles. Further comprising an O ₂ -blocking layer, the second multilayer film is one selected from the group consisting of ethylene / vinyl alcohol copolymer, polyvinyl chloride, polyvinylidene chloride, polyamide, polyester, polyacrylonitrile An O ₂ -blocking layer containing the above is further included. Preferably, the O ₂ -blocking layer of the first multilayer film has the same chemical composition as that of the second multilayer film.

As a third aspect, the present invention relates to a packaged product comprising a package and a product wrapped by the package. The package comprises a product according to the invention, preferably a preferred product according to the invention. Products include tools and hardware (for civil and military), machinery parts, instruments, marine hardware (e.g. anchors, accessories, etc.), corrosive metal products, industrial parts containing rust inhibitors, powdered chemicals and concentrates (especially Bulk packaged photographic chemicals), industrial cartridge packs, toys, bearings, dried pet food, mainly buckets, especially those packed in heavy 5 gallon buckets Cut non-assembled wood products, mainly packed in woven bags, products requiring packaging as a practical barrier against atmospheric oxygen, coffee, hops, shrimp, peanuts, postal parcels, heat resistant pouches, viscous fluids, explosives, frozen Products (especially frozen foods such as frozen juices, frozen juice concentrates, food purees, especially frozen puree of fruits and / or vegetables), ballistics, textiles (ready-made and household clothing), furniture, products dangerous for children (Ie, flexible packaging that children cannot play), fertilizers and grains (especially overseas shipments), plants (especially potted plants), insecticides and other toxic and harmful chemicals, and flood control One or more species selected from the group consisting of sandbags, water, seeds, skis, antiques and art, firewood, timber, tires and occult blood specimens.

The present invention relates to film or sheet products converted into bags, pouches, and the like, which can provide high strength packaging for the packaging of a wide range of industrial and consumer products. Such products suffer a great risk of wear and / or perforation.

1 is a schematic plan view of a preferred end-sealing bag according to the present invention.

2 is a schematic plan view of a preferred side seal bag according to the present invention.

3 is a schematic plan view of a preferred pouch according to the present invention.

4 is a cross-sectional view of a first preferred multilayer film suitable for use in the article illustrated in FIGS. 1-3.

5 is a cross-sectional view of a second preferred multilayer film suitable for use in the article illustrated in FIGS. 1-3.

6 is a schematic diagram of a preferred process for making the multilayer film illustrated in FIGS. 4 and 5.

As used herein, the term "lay-flat film" is generally extruded as a large, thin, round tube, which is blown, cooled and collected by a set of converging rollers and wound in a flat form. Say film. The term "flat pressed width" refers to half the circumference of a swollen film tube.

The term "film" as used herein generally includes a plastic web, regardless of whether the plastic web is a film or a sheet. Preferably, the film used in the present invention has a thickness of 0.25 mm or less. As used herein, the term "packaging material" refers to a packaging material disposed around a product to be packaged. As used herein, the term "packaged product" refers to a combination of products wrapped by packaging materials.

As used herein, the term "sealing" refers to the sealing of the first region of the first surface to the second region of the film surface at the film surface, wherein the sealing is formed by heating the regions to at least each sealing onset temperature (ie, , Heat seal). Sealing can be performed in one or more different ways, for example using heated rods, hot air, hot wires, infrared radiation, ultrasonic sealing, high frequency sealing, and the like.

Melting is the process of joining two or more thermoplastic films or sheets by heating the areas that are in contact with each other, usually under pressure, to the temperature at which the bonding takes place. Heat is applied by a die or a rotating wheel maintained at a constant temperature, and this process is called heat sealing. In melt-bead sealing, narrow strands of molten polymer are extruded along one surface, which is advanced by a wheel that presses both surfaces together. In an impulse seal, heat is applied by a resistance element that is rapidly heated after being applied to a job when it is relatively cold. Simultaneous performance of sealing and cutting can be performed in this way. Dielectric sealing is performed using polar materials by inducing heat in the film by high frequency. When heating is performed by ultrasonic vibration, this process is called ultrasonic sealing.

As used herein, the terms "food contact layer" and "meat contact layer" refer to one layer of a multilayer film that is in direct contact with food / meat in a packaging comprising the film. In a multilayer film, the food contact layer is always the outer film layer because it is in direct contact with the food in the packaging. The food contact layer is the inner layer, as seen for the packaged food, the food contact layer is the inner layer of the packaging material (ie, the innermost layer), and the inner layer is in direct contact with the food. As used herein, the terms “food contact surface” and “meat contact surface” refer to the outer surface of the food contact layer, which is in direct contact with the food in the package.

The term "EVOH" as used herein refers to an ethylene vinyl alcohol copolymer. EVOH includes vinyl alcohol copolymers having ethylene comonomers, including saponified or hydrolyzed ethylene vinyl acetate copolymers, for example produced by hydrolysis of vinyl acetate copolymers or by chemical reaction with polyvinyl alcohol. Say. The degree of hydrolysis is preferably about 50 to 100 mol%, more preferably about 85 to 100 mol%.

As used herein, the terms "blocker" and "blocker layer" refer to a film or film layer that acts as a barrier to one or more gases when used in connection with the film and / or film layer. In the field of packaging, oxygen (i.e. gas phase O ₂ ) barrier layers are represented by the abbreviations of hydrolyzed ethylene / vinyl acetate copolymers ("EVOH" and "HEVA"), for example, known to those skilled in the art, "ethylene / vinyl Alcohol copolymers), polyvinylidene chloride, polyamide, polyester, polyacrylonitrile and the like.

As used herein, the terms "abuse layer" and "puncture resistant layer" refer to an outer film layer and / or resistant to causes of wear, perforation and other possible loss of integrity of the packaging material. Means an inner film layer.

As used herein, the terms "lamination", "laminate" and "laminated film" refer to processes and products obtained by combining two or more film layers or other materials. Lamination can be performed by bonding the layers with an adhesive, bonding by heat and pressure while corona treating, and by spray coating and extrusion coating. The term laminate also includes coextruded multilayer films that include one or more tie layers.

As used herein, the term "stretching" refers to a polymer-containing material in which the stretched form is "fixed" by stretching (at a high temperature, typically at the stretching temperature), and then cooling the material while substantially maintaining the stretched dimensions. Say. This combination of stretching at high temperatures and subsequent cooling causes a significant change in the mechanical properties of the film by causing a structure that is more parallel to the arrangement of the polymer chains. Heating the stretched film, which is not restrained and not annealed, to the stretching temperature causes the film to heat shrink to approximately its original dimensions (ie, pre-extension). The term "stretching" as used herein refers to a stretched film that can be stretched in one or more of a variety of ways.

Stretching in one direction is referred to herein as "uniaxial stretching" and stretching in two directions is referred to as "biaxial stretching". In the stretched plastic film, there may be internal stress remaining in the plastic sheet that can be removed by reheating the film to a temperature higher than the stretched temperature. Reheating such a film tends to shrink and return to the original dimensions it had before being stretched. Films that shrink when heated are generally referred to as heat shrinkable films.

The term "stretch ratio" as used herein refers to the product of the extent to which plastic film material is stretched in several directions, usually in two directions perpendicular to each other. Stretching in the machine direction is called "drawing", while stretching in the transverse direction is called "stretching". In the case of a film extruded through an annular die, lateral stretching is obtained by blowing the film to produce a bubble. For such films, longitudinal stretching causes the film to have two sets of powered nip rolls (the rear set has a faster surface speed than the front set, and the longitudinal draw ratio is the surface speed of the nip rolls of the rear set of nip rolls). Obtained by dividing by the surface speed of the roll). The degree of stretching refers to the stretching ratio, also known as the "racking ratio".

As used herein, the term “monomer” refers to a relatively simple compound that generally contains carbon and has a low molecular weight that can react with itself or other similar molecules or compounds to form a polymer.

As used herein, the term “comonomer” refers to the amount of copolymerization with one or more other monomers in a copolymerization reaction, with the result being a copolymer.

As used herein, the term "polymer" refers to the product of a polymerization reaction and includes homopolymers, copolymers, terpolymers, quaternary copolymers, and the like. In general, the polymer of the film may consist essentially of one polymer or may have additional polymers blended with it.

The term "homopolymer" as used herein refers to a polymer resulting from the polymerization of one monomer, ie a polymer consisting essentially of one type of repeat unit.

As used herein, the term "copolymer" refers to a polymer formed by the polymerization of two or more different monomers. For example, the term "copolymer" includes the copolymerization product of ethylene and an alpha-olefin such as 1-hexene. The term "copolymer" includes, for example, copolymers of mixtures of ethylene, propylene, 1-hexene and 1-octene. As used herein, the term "copolymerization" refers to the simultaneous polymerization of two or more monomers. The term "copolymer" includes random copolymers, block copolymers and graft copolymers.

The term "polymerization" as used herein includes homopolymerization, copolymerization, terpolymer polymerization, and the like, and includes all types of copolymerizations such as random, graft, block, and the like. In general, the polymers in the films used according to the invention can be prepared according to suitable polymerization processes including slurry polymerization, gas phase polymerization and high pressure polymerization processes.

As used herein, a copolymer represented by a plurality of monomers, such as a "propylene / ethylene copolymer," refers to a copolymer that is capable of copolymerizing one equivalent to a higher molecular weight or mole percent higher than the other monomer or monomers. Say. However, the first monomer described above is preferably copolymerized at a higher molecular weight% than the second described monomer, and in the case of copolymers such as terpolymers, quaternary copolymers, etc., preferably the first monomer has a higher molecular weight than the second monomer. The copolymerization is performed at%, and the second monomer is copolymerized at a molecular weight% greater than that of the third monomer.

As used herein, the term using “/” in the chemical class of the copolymer (eg “ethylene / alpha-olefin copolymer) refers to a comonomer that copolymerizes to produce the copolymer. The "ethylene alpha-olefin copolymer" used is the same as the "ethylene / alpha-olefin copolymer".

As used herein, a copolymer is named by the monomer from which the copolymer is produced. For example, the term "propylene / ethylene copolymer" refers to a copolymer produced by copolymerization of propylene and ethylene in the presence or absence of additional comonomer (s). As used herein, the term “monomer unit” refers to polymer units derived from monomers used in the polymerization reaction. For example, the term "alpha-olefin monomer unit" refers to a unit in, for example, an ethylene / alpha-olefin copolymer, wherein the polymer unit is part of the polymer chain, that is, part of the polymer, so that part of the polymer chain chain is reacted. It is the "residue" derived from the alpha-olefin monomer after becoming part of the polymer occupied by the individual alpha-olefin monomer after being added.

As used herein, the term "heterogeneous polymer" refers to a polymerization reaction product having a relatively broad molecular weight distribution and a relatively broad compositional distribution, i.e., a polymer made using a conventional Ziegler-Natta catalyst. Heterogeneous polymers are useful in various layers of the films used in the present invention. Such polymers typically have a relatively wide chain length and comonomer ratios.

As used herein, the term “heterogeneous catalyst” refers to a catalyst suitable for use in the polymerization of heterogeneous polymers as defined above. Heterogeneous catalysts consist of several active sites that differ in Lewis acidity and steric environment. Ziegler-Natta catalysts are heterogeneous catalysts. An example of a Ziegler-Natta heterogeneous system is a metal halide (optionally containing magnesium chloride) activated by an organometallic promoter such as titanium chloride, complexed with trialkyl aluminum, and Goeke. US Pat. No. 4,302,565 to US Pat. No. 4,302,565 and US Pat. No. 4,302,566 to Karol et al., Which are incorporated herein by reference.

The term “homogeneous polymer” as used herein refers to a polymerization reaction product having a relatively narrow molecular weight distribution and a relatively narrow composition distribution. Homogeneous polymers can be used in various layers of multilayer films useful in the present invention. Homogeneous polymers exhibit relatively even comonomer sequences in the chain, reflection of the sequence distribution of all chains and similarity of all chain lengths (ie narrow molecular weight distribution). In addition, homogeneous polymers are typically prepared using metallocenes or other single site catalysts, rather than using Ziegler-Natta catalysts.

More specifically, homogeneous ethylene / α-olefin copolymers are prepared by one or more methods known to those skilled in the art, for example molecular weight distribution (M _w / M _n ), composition distribution width index (CDBI), narrow melting point range and It can be characterized by a single melting point behavior. The molecular weight distribution (M _w / M _n ), also known as "polydispersity", can be determined by gel permeation chromatography. Homogeneous ethylene / α- olefin copolymer that can be used in the present invention is preferably less than 2.7 of M _w / M _n, and more preferably about 1.9 to 2.5 to a M _w / M _n, more preferably from about 1.9 to M _w / M _n of 2.3. The composition distribution width index (CDBI) of the homogeneous ethylene / α-olefin copolymer is generally at least about 70%. CDBI is defined as the weight percent of copolymer molecules having a comonomer content that falls within 50% (ie, ± 50%) of the average total comonomer molar amount. The CDBI of linear polyethylene without comonomers is defined as 100%. The composition distribution width index (CDBI) is determined by the elevated temperature elution fractionation (TREF) method. By CDBI crystals, homogeneous copolymers with commercially available VLDPE having a broad compositional distribution, generally evaluated by CDBI values of less than 55% (i.e., narrow composition distributions, generally evaluated by CDBI values higher than 70%) Have distinction). TREF data and calculations for CDBI determination of copolymers are described, for example, in Wild et al. Poly. Sci. Poly. Phys. Ed., Vol. 20, 441 (1982), which is readily calculated from data obtained by techniques known in the art, such as elevated temperature elution fractionation methods. Preferably, the homogeneous ethylene / alpha-olefin copolymer has a CDBI greater than about 70% (ie, CDBI is about 70-99%). In general, homogeneous ethylene / alpha-olefin copolymers useful in the present invention also exhibit a relatively narrow melting point range compared to “heterogeneous copolymers” (ie, polymers with a CDBI of less than 55%). Preferably, the homogeneous ethylene / alpha-olefin copolymer has an essentially single melting point, with a peak melting point (T _m ) of about 60 to 105 ° C. as measured by differential scanning calorimetry (DSC). Preferably, the homogeneous copolymer has a DSC peak T _m of about 80 ° C to 100 ° C. As used herein, the term “essentially single melting point” means that at least about 80% by weight of the material, as measured by DSC analysis (eg, on a Perkin Elmer ^™ System 7 thermal analysis system), is 60-105 ° C. Corresponds to a single T _m peak at a temperature in the range, which essentially means that a substantial portion of the material does not have a peak melting point above about 115 ° C. DSC measurements are taken on a Perkin Elmer System 7 thermal analysis system. The reported melting point information is another melting point data. That is, the sample is heated to a temperature below the critical range at a programmed rate of 10 ° C./min. The sample is then reheated at a programmed rate of 10 ° C./min (second melting point).

Homogeneous ethylene / alpha-olefin copolymers can generally be prepared by copolymerization of ethylene and one or more alpha-olefins. Preferably the alpha-olefin is a C ₃ -C ₂₀ alpha-monoolefin, more preferably a C ₄ -C ₁₂ alpha-monoolefin, even more preferably a C ₄ -C ₈ alpha-monoolefin. Even more preferably, the alpha-olefin comprises one or more selected from the group consisting of butene-1, hexene-1 and octene-1 (ie 1-butene, 1-hexene and 1-octene). Most preferably, the alpha-olefins comprise octene-1 and / or a blend of hexene-1 and butene-1.

Methods for making and using homogeneous polymers are described in US Pat. No. 5,206,075 to Hodgson, Jr., US Pat. No. 5,241,031 to Mehta, and International Patent Publications, incorporated herein by reference. It is described in publication WO 93/03093. For further details on the preparation and use of homogeneous ethylene / alpha-olefin copolymers, see International Patent Publication No. WO, filed by Exxon Chemical Patents Inc., which is incorporated herein by reference. 90/03414 and WO 93/03093.

Still other classes of homogeneous ethylene / alpha-olefin copolymers are described in US Pat. No. 5,272,236 to Lai et al. And US Pat. No. 5,278,272 to Lai et al., Which are incorporated herein by reference.

The term "polyolefin" as used herein refers to a polymerized olefin which is linear, branched, cyclic, aliphatic, aromatic, substituted or unsubstituted. More specifically, the term polyolefin includes copolymers such as homopolymers of olefins, copolymers of olefins, olefins and non-olefin comonomers (eg vinyl monomers) copolymerizable with olefins, modified polymers thereof and the like. Specific examples include polyethylene homopolymer, polypropylene homopolymer, polybutene, ethylene / alpha-olefin copolymer, propylene / alpha-olefin copolymer, butene / alpha-olefin copolymer, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylic Acrylate copolymers, ethylene / butyl acrylate copolymers, ethylene / methyl acrylate copolymers, ethylene / acrylic acid copolymers, ethylene / methacrylic acid copolymers, modified polyolefin resins, ionomer resins, polymethylpentenes, and the like. Modified polyolefin resins include modified polymers prepared by copolymerization of homopolymers or copolymers of olefins with unsaturated carboxylic acids (such as maleic acid, fumaric acid, etc.) or derivatives thereof (such as anhydrides, esters or metal salts, etc.). . Modified polyolefin resins can be obtained by introducing unsaturated carboxylic acids (such as maleic acid, fumaric acid, etc.) or derivatives thereof (such as anhydrides, esters, or metal salts) into olefin homopolymers or copolymers.

As used herein, terms referring to polymers such as "polyamide", "polyester", "polyurethane" and the like refer to polymers comprising repeating units derived from monomers known to form polymers named by polymerization. Comonomers, derivatives, and the like, which are copolymerizable with monomers known to form polymers named by polymerization. For example, the term "polyamide" refers to polymers comprising repeating units derived from monomers (e.g. caprolactam) which form polyamides by polymerization and comonomers which do not form polyamides when polymerized alone. Copolymers derived from copolymerization of caprolactam. The term referring to a polymer also includes “blends” of the polymer with other types of other polymers.

As used herein, the terms "ethylene alpha-olefin copolymer" and "ethylene / alpha-olefin copolymer" refer to low density polyethylene (LDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), very low density polyethylene ( Heterogeneous materials such as VLDPE) and ultra low density polyethylene (ULDPE); And metallocene-catalyzed EXACT ^™ linear homogeneous ethylene / alpha olefin copolymer resins available from Exxon Chemical Company, Baytown, Texas, USA, homogeneous substantially with long chain branches Ethylene / alpha-olefin copolymer linear (AFFINITY ^™ resin and ENGAGE ^™ resin available from The Dow Chemical Company, Midland, Mich.), And Homogeneous ethylene / alpha olefin copolymers such as TAFMER ^™ linear homogeneous ethylene / alpha-olefin copolymer resins available from Mitsui Petrochemical Corporation. The above-mentioned heterogeneous polymers and homogeneous polymers include one or more comonomers selected from C ₄ -C ₁₀ alpha-olefins such as butene-1 (ie 1-butene), hexene-1, octene-1, etc.) There is a copolymer of ethylene. LDPE and MDPE are more branched than LLDPE, VLDPE, ULDPE, IgJack resins, and Tampher resins, but the latter group of resins have relatively shorter branches than the long chain branches present in LDPE and MDPE. Affinity and Engage resins have a relatively large number of short chain branches with a relatively small number of long chain branches. LLDPE usually has a density of about 0.91 g / cm 3 to about 0.94 g / cm 3.

Generally, the ethylene / alpha-olefin copolymers comprise copolymers resulting from the copolymerization of about 80 to 99 weight percent ethylene and 1 to 20 weight percent alpha-olefin. Preferably, the ethylene / alpha-olefin copolymer comprises a copolymer resulting from the copolymerization of about 85 to 95 weight percent ethylene and 5 to 15 weight percent alpha-olefin.

As used herein, the terms "inner layer" and "inner layer" refer to any layer of a multilayer film whose major surface is both directly bonded to another layer of the film.

As used herein, the term "inner layer" refers to the outer film layer of the multilayer film that wraps the product closest to the product, as compared to other layers of the multilayer film. "Inner layer" is also used when referring to the innermost layer of a plurality of layers arranged concentrically coextruded through an annular die.

As used herein, the term "outer layer" means any layer of a multilayer film in which one of its major surfaces is directly bonded to the other layer of the film. The phase includes monolayer and multilayer films. Every multilayer film has two outer layers, each of which has a major surface bonded to only one other layer of the multilayer film. In a monolayer film, there is only one layer (of course, this layer is an outer layer) in which neither of the two major surfaces are bonded to the other layer of the film.

As used herein, the term "outer layer" means the outer layer of the multilayer film for packaging the product, the furthest from the product relative to the rest of the multilayer film. "Outer layer" is also used to refer to the outermost layer of a plurality of layers arranged concentrically coextruded through an annular die.

As used herein, the term "direct bonding" as applied to a film layer means that the main film layer binds to the object film layer without a tie layer, an adhesive, or another layer between these layers. In contrast, the term “between” when used for a film layer between two different particular layers, not only is the subject layer directly bonded to both sides between the two different layers, but also between the two different layers. In which there is no direct bonding on one or both sides (ie, one or more additional layers can be placed between the subject layer and one or more layers covered by the subject layer).

As used herein, the terms “core” and “core layer” refer to any inner film layer that has a primary function except for its function as an adhesive or compatibilizer to bond the two layers together when used for a multilayer film. . In general, the core layer or core layers provide the multilayer film with the desired degree of strength (i.e., modulus and / or optical and / or added anti-reflective and / or specific impermeability).

The terms "sealing layer", "sealing layer" and "sealant layer" refer to a film for itself, for another film layer of the same film or another film, and / or for a product other than the film. Refers to the outer film layer or layers involved in sealing. It should be appreciated that generally no more than three millimeters of the outer side of the film may be involved in the sealing of the film to the film itself or other layers. With respect to packaging materials having fin-like seals, as opposed to lap-like seals, the term "sealing layer" generally refers to the inner film layer of the packaging material, as well as the inner, which often acts as a food contact layer in the packaging of food. The support layer within 3 mils of the inner surface of the sealing layer. In general, hermetic layers used in the packaging sector have included thermoplastic polymers such as polyolefins, polyamides, polyesters and polyvinyl chlorides.

As used herein, the term "tie layer" refers to an inner film layer whose main purpose is to bond the two layers together. The tie layer may be any polymer having polar groups or any other polymer sufficient to bond the inner layer to an adjacent layer comprising a non-bonding polymer.

The term "skin layer" as used herein refers to the outer layer of the multilayer film in the packaging of the product, which surface is prone to overuse.

As used herein, the term "bulk layer" refers to any film layer with the purpose of increasing the resistivity, toughness, modulus, etc. of the multilayer film. Bulk layers include polymers that are not expensive compared to other polymers in films that serve several specific purposes not related to puncture resistance, modulus, and the like.

As used herein, "first layer", "second layer" generally refers to how the multilayer film structure is constructed. That is, generally the first layer can be present without describing additional layers, or the first layer and second layer can be present without describing additional layers.

As used herein, the term “extrusion” refers to a process of forcing molten plastic material into a die and cooling or chemical curing to form a continuous form. Immediately before extruding through the die, a relatively high viscosity polymer material is fed to a rotating pitch of various pitches (ie, an extruder), which forces the polymer material into the die.

As used herein, the term “coextrusion” refers to a process of combining the products of two or more extruders into a feed block to form a multilayer stream that is fed to a die to produce a layered extrudate. Coextrusion can be used for film blowing, sheet and flat film extrusion, blow molding and extrusion coating.

As used herein, the term "machine direction" (abbreviation "MD") means the "length direction" of the film (ie, the direction of the film formed during extrusion and / or coating). As used herein, the term "lateral direction" (abbreviated "TD") means the width direction of the film perpendicular to the machine direction or the longitudinal direction.

As used herein, the term “free shrinkage” refers to the rate of dimensional change when a 10 cm × 10 cm film specimen shrinks at 185 ° F., and quantitative analysis is described in the 1990 Annual Book of ASTM Standards, Vol. 08.02, pp. 368-371, according to ASTM D 2732.

Films useful in the articles of the invention have at least one layer (more preferably 1 to 20 layers), more preferably the film has 1 to 12 layers, even more preferably 1 to 8 layers, even more preferably Has 1 to 4 layers. However, if the multilayer film has three or more layers, the multilayer film may have desirable properties (e.g., O ₂ -blocking properties, free shrinkage, shrinkage tensile, optical properties, modulus, sealing strength, etc.) for the particular packaging process in which the film is used. ), It can further have the required number of layers. The multilayer film shown in FIG. 2 has four layers. However, since the intermediate layer is preferably formed by pressing two layers of tube films on itself, the intermediate layer is actually two distinct layers so that the film actually contains four layers.

The film used in the present invention has a thickness of at least 1.5 mils (1 mil = 0.001 inch), preferably about 1.5 to 20 mils, more preferably about 2 to 20 mils, even more preferably about 3 to 7 mils And even more preferably about 4 to 5 mils. Of course, the preferred thickness varies depending on the properties desired for the particular packaging process in which the film is used.

1 is a side view of a preferred product (end seal bag) according to the present invention. In FIG. 1 the end seal bag 10 is shown in a flat pressed position. The end seal bag 10 is made from a film 12, the end seal bag 10 having an open top 14 and end seal 16.

2 is a side view of another preferred product (side seal bag) according to the invention. In FIG. 2 the end seal bag 20 is shown in a flat pressed position. The side seal bag 20 is made from a film 12, the side seal bag having an open top 22 and side seals 24, 26.

3 is a side view of another preferred product (pouch) according to the present invention. In FIG. 3 the pouch 30 is shown in a flat pressed position. Pouch 30 is also made from film 12 and has an open top 32, side seals 34, 36 and end seals 38.

4 shows a cross-sectional view of a preferred four-layer film 12 for use as a material for making the bags of FIGS. 1 and 2 and the pouches of FIG. 3. Film 12 has a first outer film layer, first layer 42, inner film layers 44, 46, and second outer film layer 48. The cross section of the film 12 is preferably symmetrical. That is, it is symmetrical in terms of thickness and chemical composition. The outer layer is preferably much thicker than the inner layer. Preferably, film 12 is produced by pressing a two-layer tube on itself to produce a symmetric four-layer film. Since the inner film layer is actually made from the same layer of pressed tubular film, the two inner film layers are one layer for all practical purposes. The dotted line in FIG. 4 shows the junction of the inner layer of the tube bonded to itself.

5 is a cross-sectional view of another multilayer film 50 that can be used as a material for making a product according to the present invention. The multilayer film 50 is a seven-layer film, described in detail in film 19 below. The multilayer film 50 includes an outer layer 52, a bulk layer 54, a tie layer 56, an O ₂ -blocking layer 58, a tie layer 60, a bulk layer 62, and an outer layer 64. Is done.

6 is a schematic diagram of a preferred process for producing the multilayer films of FIGS. 4 and 5. In the process shown in FIG. 6, solid polymer beads (not shown) are fed to a number of extruders 66 (only one extruder is shown for simplicity). Inside the extruder 66, after the polymer beads are advanced, melted, and degassed, the resulting bubble-free melt is sent to the die head 68 and extruded through an annular die, having a thickness of 5 to 40 mils, more preferably. Preferably 20 to 30 mils, even more preferably about 25 mils of tube 70 are produced.

After cooling or quenching by cooling water from cooling ring 72, tube 70 is pressed by pinch roll 74 and then irradiation vault wrapped by shielding 78. In the irradiation bolt, the tube 70 is irradiated with high-energy electrons (ie, ionizing wire) from the iron core transformer accelerator 80. The tube 70 is guided on the roll 82 past the irradiation bolt 76. Preferably, the dose of tube 70 is about 2-10 megarads (hereinafter referred to as "MR"), more preferably about 3.5-4MR.

After irradiation, the irradiated tube 84 is sent onto a guide roll 86 and then the irradiated tube 84 is passed through a hot water bath 88 containing water 90. The irradiated tube 84 in the depressed state is immersed in hot water for a residence time of at least about 5 seconds, ie, for a time sufficient to bring the film to the desired temperature, and then the irradiated tube 84 is partially wound up. Auxiliary heating means (not shown), including a plurality of steam rolls and an optional hot air blower, raise the temperature of the irradiated tube 84 to a desired stretching temperature of about 240 ° F to 250 ° F. Then, the irradiated film 84 is sent to the nip roll 92, and blown into a bubble 94, so that the irradiated tube 84 is stretched in the transverse direction, and the stretched blown tubular film 96 is stretched. Is formed. In addition, during the blowing, i.e., while stretching in the transverse direction, the nip roll 98 has a surface speed that is higher than the surface speed of the nip roll 92, so that the nip roll 88 and the nip roll 98 are separated. The irradiated tube 84 is longitudinally stretched (ie, longitudinally). As a result of the transverse stretching and longitudinal stretching, an irradiated, biaxially stretched, blown tubular film 96 is produced, which is preferably transversely stretched in a ratio of about 1: 1.5 to 1: 1.6, and about 1: 1.5 to It is longitudinally stretched at a ratio of 1: 1.6. More preferably, transverse stretching and longitudinal stretching are performed at a ratio of about 1: 2 to 1: 4, respectively. The result is a biaxial stretching of about 1: 2.25 to 1:36, more preferably 1: 4 to 1:16.

While the bubble 94 is held between the pinch rolls 92 and 98, the blown tubular film 96 is pressed by the converging roll 100 and then passes through the pinch roll 98 to guide the roll 102. After being transported through, it is wound on a take-up roller 104. Idler roll 106 helps to wind up.

Various films suitable for use in the products of the present invention are illustrated by the following examples. Unless stated otherwise, all percentages, parts, etc., are by weight.

Example 1 Film 1

A co-extruded two-ply tubular tape is cast, which has a thickness of 29 mils, layer A, which accounts for 85% or less of the tape thickness, and layer B, which occupies 15% or less of the tape thickness. Layer A is (a) a DOWLEX 2045 ^™ linear low density polyethylene (hereinafter referred to as "LLDPE # 1") with a density of 0.920 g / cc from The Dow Chemical Company, Midland, Michigan, USA. 87% by weight; (b) ELVAX 3128 ^™ ethylene / vinyl acetate copolymer (hereinafter referred to as "EVA # 1") with a vinyl acetate content of 10% obtained from DuPont, Wilmington, Delaware, USA. 10% by weight; And (c) TEKNOR EPE-9612C ^™ Block Protector (hereinafter referred to as "block protector # 1") from the Teknor Apex Plastics Division of Porterett, Rhode Island, USA. 3% by weight). Layer B is an Exact SLP 4008 linear homogeneous ethylene / alpha-olefin plastomer, obtained from Exxon Chemical Company, Baytown, Texas, USA (hereafter referred to as "Linear Homogeneous Ethylene Alpha Olefin # 1"). ") 100% by weight.

The 2-ply tube was cooled to solid in the water bath and then electronically crosslinked by irradiation with a radiation dose of about 2-10MR using a 500Kev beam. The resulting crosslinked two-ply tube was heated by steam cans and hot air at about 210-220 ° F., and then about 350 each in the machine and transverse directions, using the trapped air bubbles contained between the two nip rolls. Stretching was done by% longitudinal stretching and transverse stretching. As a result of the stretching, a two-ply film having a thickness of 2.25 mil in the form of a tube was produced.

After longitudinal stretching, if the resulting tube of hot water-shrinkable flat film passes through a pair of nip rolls, the inner B layer is bonded to itself when the tube is pressed, resulting in a four-ply film as shown in the table below, The "middle" ply is then the inner B layer bonded to it (ie it becomes a 4.5 mil "four ply" film):

A Blend A B SLP 4008 B SLP 4008 A Blend A

Table I below shows the function of each layer in the film along with the chemical composition and thickness of each layer:

Floor Location / Floor Functions Chemical composition Layer thickness (mils) Outer / inner perforated layer LLDPE # 1 87% EVA # 1 10% Block Agent # 1 3% 2.0 Core / Tie Layer Homogeneous Ethylene / Alpha-olefin # 1 0.7 Inner / inner perforated layer LLDPE # 1 87% EVA # 1 10% Block Agent # 1 3% 2.0

Film number 1 consists of these three layers, with the middle layer consisting of an inner tube layer bonded to itself. Film 1 was determined to free shrink at 185 ° F. (according to ASTM 2732) and to have an instrumented impact as described in Table II below. Instrument impact was measured by substantially the same procedure as ASTM D 3763. ASTM D 3763 is described in 1990 Annual Book of ASTM Standards, Section 8, Plastics, Vol. 08.03, pp. 174-178.

The replacement for film # 1 is a two-layer film having a thickness of about 4.5 mils, wherein about 85% by weight of the film has a composition corresponding to layer 38 described in Table I above, and about 15% by weight of this film is 40). This film could be produced using flat dies rather than circular dies.

Example 2: Film 2

Film No. 2, the layer A (a) 87% by weight of LLDPE # 1; (b) Igact 3032 ^™ linear homogeneous ethylene / alpha-olefin plastomer, obtained from Exxon Chemical Company, at a density of 0.900 g / cc (hereinafter referred to as "linear homogeneous ethylene / alpha-olefin copolymer # 2"). 10% by weight; And (c) 3% by weight of Blocking Agent # 1, except that it was prepared by the same process as used to produce film # 1. In film 2, layer B was the same as layer B of film 1. In addition, as in film 1, in film 2, layer A occupied 85% or less of the tape thickness, and layer B occupied 15% or less of the tape thickness. Free shrinkage and instrument impact of film # 2 are provided in Table III below.

Example 3: Film 3

Film 3 is irradiated at about 3.5 to 4MR (about half of the dose used to make all other films disclosed herein; this dose improves the sealability of the outer film layer), and layer A (a ) LLDPE # 1 87% by weight; (b) Elbox 3128 ethylene / vinyl, with a vinyl acetate content of 9%, a density of 0.928 g / cc and a melt index of 2.0, obtained from DuPont Chemical Co., Wilmington, Delaware, USA. 10% by weight acetate copolymer (hereinafter referred to as "EVA # 2"); And (c) 3% by weight of Blocking Agent # 1, except that it was prepared by the same process as used to produce film # 1. In film 3, layer B was obtained from DuPont Chemical Company, Wilmington, Delaware, USA, with a vinyl acetate content of 28%, a density of 0.950 g / cc and a melt index of 6.0. Box 3175 ^™ consisted of 100% by weight of ethylene / vinyl acetate copolymer. In addition, as in film 1, in film 3, layer A occupied 85% or less of the tape thickness, and layer B accounted for 15% or less of the tape thickness. Free shrinkage and instrument impact of Film 3 are provided in Table III below.

Using the film according to Example 3, a side seal bag was produced having dimensions of about 7 inches wide and about 12 inches high. The film is a VERTROD® impact seal using a ribbon-shaped sealing element having a width of about 0.25 inches and the (folded) film is forced against the film itself and the sealing element by means of an upper jaw. Was applied for about 5 seconds using a pressure of about 50 psi. The resulting side seal bag was filled with 5 pounds of corn, and then the top of the bag was sealed in a similar manner to the side seal. About 10 packages were made. The package was then dropped about 35 feet above the concrete. Six packages were unharmed without film damage or seal damage. Surprisingly, the four damaged packages showed no sealing damage. Rather, there was film damage in the area of the film proximate the seal. This area proximate to the seal was actually thicker than the rest of the bag because it was heated and retracted (ie thickened) by the seal rod during the sealing process. However, this area also decreased in stretching while shrinking and thickening. This reduction in stretching is thought to be the cause of damage due to impact of the film in this region. That is, the stretching of the polymer in the remainder of the film is believed to provide a stronger film than the area adjacent to the seal, which undergoes a decrease in stretching during the sealing process. Thus, it has been found that relatively thick films can be sealed in a manner that provides a stronger seal than the film area proximate the seal. The limiting burst strength factor is not the strength of the seal itself, but the strength of the film in the region adjacent to the seal. A similar test was carried out with a 20 pound TRAYBLAZER® dry pet dog food, 25 pounds CLEAN PAWS® cat litter (where the seal is described below with a radial wire as described below). ) And 15 pounds of Feeders CHOICE® bird feeders, provided that the seal consists of radial wires as described below, with similar results (ie, About 60% of the packages were safe).

Other tests were made by fabricating the side seal bags, this time using a butt rod sealer modified to simulate a bag with a condition of 0.0937 inches of radial wire (instead of the 1/4 inch ribbon described above) and a pressure of about 50 psi. The heating time of about 0.9 seconds followed by the cooling time of 0.3 seconds, the potential of the current through the heated wire was 38 volts. The resulting bag was placed between parallel walls about 3-4 inches apart (ie, "parallel rupture test") and then the bag was inflated until one of the side seals was damaged. As in the drop test results presented above, damage always occurred in the region adjacent the seal. The seal was not damaged. The pressure inside the bag at the time of injury was a measure of strength. Bags made from the film according to Example 3 had an average burst strength of 522 inches of water in the parallel plate rupture test, and the strength was almost constant (i.e., a range from about 430 inches of water to about 640 inches of water). . In contrast, the smaller, non-crosslaminated film exhibited a lower parallel plate burst strength, for example, about 100 to 150 inches of water, compared to a film of about 2 mils in total thickness.

The drop test was carried out by superimposing eight reams of paper (each rim was individually wrapped in paper) in the film of Example 3 sealed to itself and shrunk by a heat gun. The weight of the package was approximately 47 pounds. The film was sealed by a Welldotron 6402 (L) rod sealer, the tap selector of the sealer was set to "6" and the compensator gap was ¼ inch. Was set. After shrinking, the "master package" was dropped at a height of about 4 feet. The paper was superimposed on the burst individual packaging, but the film or seals did not rupture.

Pouches were made from folded films. Sealing was done using a Welldotron 6402 "L" bar sealer. The resulting seal, when measured by an Instron Series IX material test system, exhibited an average seal strength of greater than 17 pounds per inch of straight line. “Exceeding” 17 pounds is the result of Joe's inability to keep the sample in the clamp.

Film 3 was made with three different variations that varied only the dosage used. The first variant was not investigated at all. The second variant was irradiated at 25 milliamps (3.5MR, ie 49 kilolog). The third modification was investigated at 49.5 milliamps (7MR, 98 kGy). Each of these film variants was transformed into a side seal bag that was 5½ inches wide and 13 inches long in a flat pressed state using a modified butt machine (described below).

The film (and bag) made from each of the three variants of film 3 was then subjected to US Pat. No. 4,355,076 to Duggan J. Gash and / or US Pat. No. 4,243,463, also to Gash. Compared to the prepared VALERON® cross-laminated film (and simply molded bag). Two valeron chrominated films were compared with the product according to the invention. One was about 4 mils thick and the other was about 6 mils thick.

Three different comparative tests were performed: (1) parallel plate tear test; (2) butte rod seal strength test; And (3) Weldotron Transverse Trim Seal Strength Test. The parallel plate burst test defines a 5 "x 13" side seal bag (made of the material to be tested, sealing the material to be tested to itself with a butt sealer to form a bag) and then rupturing the bag. Inflate until performed. The pressure level inside the bag at the time of rupture was considered a measure of seal quality. Results were reported in inches of water pressure (IOWP).

The butt rod seal strength test was carried out in a bag with a seal made using a butt rod sealer (obtained from Butt Rod Corporation, Brooklyn, NY) that modified the sealing process more precisely. That is, the butt seal was modified to provide a preheating time of 0.6 seconds, a sealing time of 0.6 seconds, and a cooling time of 0.2 seconds. Although the voltages of 20, 30, 35, 40 and 45 were used in the sealing of the film tested, the butt sealer was operated at 40 and 45 volts, which appeared to be effective to achieve the desired sealing (ie, the present invention). In the sealing of the product and valeron comparison film). After the seal was formed, a 1.0 inch × about 4 to 5 inch sample with cut parts was cut from the sealed film. This sample was applied to a "tear off" force on an Instron Tensile Tester (Instron Corporation, Canton, MD). The two pairs of Instron tensile testers are two inches apart. The greater the force required to rupture the film, the stronger the seal. The results are reported in Table II below.

Weldotron transverse trim sealing strength tests were performed using a Welldotron 6402 sealing pad. The welldotron 6402 sealing apparatus formed the rod by heating the wire through the films to be sealed together. More specifically, the Welldotron 6402 sealing device was operated at a tap setting of 6 and a calibration gap of about ¼ inch. After the seal was formed, a 1.0 inch × about 4 to 5 inch sample was cut from the sealed film. As in the butt rod seal strength test described above, the sample cut from the sealed film was laterally sealed over its midpoint. This sample was then subjected to a "tear off" force on an Instron tensile tester. The greater the force required to rupture the film, the stronger the seal.

Table II below provides the results of various films according to film 3 and the results of film 20 described hereinafter. Film 20 was similar to film 3 except that layer A of film 20 contained no ethylene / vinyl acetate copolymer. In addition, Table II provides the results for the two comparative valeron crosslaminated films.

Film type (film number) / film thickness (mils) Dose (milliampere) Parallel Plate Burst Strength (in H ₂ O) @ 40V / @ 45V Butt Rod Seal Strength (ℓb / in) @ 40V / @ 45V Weldotron 6402 Transverse Seal Strength (ℓb / in) 3 / 4.5 0 186/229 3.9 / 8.4 16.8 3 / 4.5 25 130/390 4.7 / 11.8 13.5 3 / 4.5 49.5 WNS / 235 WNS / 8.8 WNS / WNC 20 / 4.5 0 121/229 5.0 / 8.7 17.4 20 / 4.5 25 137/381 4.7 / 8.2 14.0 20 / 4.5 49.5 WNS / 251 WNS / 11.9 WNS / WNC Valeron / 4.0 do not know 179/155 7.6 / 7.1 9.9 Valeron / 6.0 do not know WNS / 351 WNS / 11.6 10.2 WNS = Not Sealed WNC = Not Cut

As can be seen from the results in Table II, the parallel plate tear strength of the side seal bags of film 3 and film 20 (using 4.5 mil multilayer uncrosslinked film, respectively) was calculated from the side seal bags produced from valeron crosslaminated film. Compared to the parallel plate burst strength is advantageous. Compare the best parallel plate burst test results of side seal bags prepared according to Examples 3-20 with the best parallel plate burst test results of side seal bags made from valeron crosslaminated films (ie, films according to Comparative Film 21). As a result, the 4.5 mil bag according to the present invention, surprisingly sealed at 45 volts in a butt sealer and irradiated at 25 milliamperes (Ma), exhibited much greater parallel plate tear strength than a 4.0 mil valeron crosslaminated film ( 390 inches and 381 inches of water for a 4.5 mil unlaminated film and 179 inches of water for a 4.0 mil valeron chrominated film). Even more surprisingly, the 4.5 mil bags according to the invention made from films 3 and 20 exhibited much higher parallel plate burst strength than the 6.0 mil valeron chrominated films (ie, water for 4.5 mil bags). 390 inches and 381 inches, and 351 inches of water for a 6.0 mil valeron chrominated film).

There is another surprising result from the butt rod seal strength test results presented in Table II. That is, when the butt rod sealing strength test of the bag according to the present invention is performed, that is, the butt rod sealing strength test of the side seal bag manufactured from the film 3 and the film 20 of the side seal bag made from the valeron cross-laminated film was performed. If performed, surprisingly 4.5 mil bags made from films 3 and 20 according to the present invention (sealed at 45 volts in a butt sealer, not irradiated or irradiated at 25 Ma or 49.5 Ma) have a sealing strength of 8.4, 11.8, 8.8, 8.7, 8.2 and 11.9 lb / in, whereas the seal strengths were 7.1 and 11.6 lb / in for seals formed using 4.0 and 6.0 mil valeron crosslaminated films. That is, the butt load strength test results of the 4.5 mil film suitable for use in the product of the present invention are very high compared to the butt load strength test results of the 4.0 mil and 6.0 mil valeron crosslaminated films. A 4.5 mil film suitable for use in the product of the present invention exhibited a butt load seal test of 108% to 156% of the strength of the 4.0 mil valerian crosslaminate film and 71% to 103% of the 6.0 mil valerian crosslaminate film. . Normalizing the Bert Rod sealing strength test results of 4.5 mil film for comparison with 6.0 mil Valeron crosslaminate film, the 4.5 mil film is about 94% to 137% of the Bert Rod sealing strength of the 6.0 mil Valeron crosslaminate film. Indicated. Thus, it is evident that the sealing strength of non-crosslaminated films suitable for use in the articles of the invention is very high compared to valeron crosslaminate films of the same thickness.

Similarly, there is another surprising result in the welldotron transverse seal strength test results presented in Table II. Well dotron sealing was performed as described above. Unlike the butt rod seal strength test, the welldotron seal strength test was performed by sealing across a film tube to form an end seal bag. However, subsequent Instron seal strength tests were performed as in the butte rod seal strength test. The results of the welldotron transverse seal strength test are provided in the right column of Table II above. Surprisingly, 4.5 mil films of the bags according to the invention, ie bags made using film 3 and film 20, have a welldotron sealing strength of 13.5 to 17.4 lb / in, while 4.0 and 6.0 mil of valeron crosslaminate In the case of the film, the well-dotron seal strength was only 9.9 and 10.2 lb / in, respectively. In other words, the welldotron sealing strength of the 4.5 mil sealed film according to the present invention is about 136% to 176% of the welldotron sealing strength of the 4.0 mil valerian crosslaminated film and the well of the 6.0 mil valerian crosslaminated film It was about 132% to 171% of the dot Ron seal strength.

Example 4: Film 4

Film 4, layer A is (a) 82% by weight LLDPE # 1; (b) 15% by weight of EVA # 1; And (c) 3% by weight of Blocking Agent # 1, except that it was prepared by the same process as used to produce film # 1. In film 4, layer B consisted of 100% by weight of EVA # 2. In addition, as in film 1, in film 4, the layer A occupied 85% or less of the tape thickness, and the layer B accounted for 15% or less of the tape thickness. Free shrinkage and instrument impact of film # 4 are provided in Table III below.

Example 5: Film 5

Film 5, layer A, (a) LLDPE # 1 67% by weight; (b) Branded experimental long-chain branched homogeneous ethylene / alpha-olefin copolymer XU59220.01 with a density of 0.901 g / cc and a melt index of 0.901 g / cc, obtained in collaboration with The Dow Chemical Company, Midland, Mich. 30% by weight of the "homogeneous ethylene / alpha-olefin # 3"; And (c) 3% by weight of Blocking Agent # 1, except that it was prepared by the same process as used to produce film # 1. The evaluation results of the films / bags containing the experimental polymers described in this example were approved to be published by Dow.

In film 5, layer B consisted of 100% by weight of EVA # 2. In addition, as in film 1, in film 5, layer A occupied 85% or less of the tape thickness, and layer B occupied 15% or less of the tape thickness.

Free shrinkage and instrument impact of film # 5 are provided in Table III below.

Film number Free shrinkage at 185 ° F% MD /% TD Free shrinkage at 205 ° F% MD /% TD Impact Strength (ℓb) Energy required for breaking (ft · lb) One 11/16 20/30 97 4.8 2 11/18 21/32 109 5.7 3 10/17 20/32 100 5.0 4 13/18 25/32 87 3.1 5 14/20 -/- 88 3.2

As can be seen from Table III, the impact strengths of the various films according to the invention, namely films 1, 2 and 5, are the impacts of films 3 and 4 using LLDPE as a polymer that gives the films high impact strength. Comparable in strength. Thus, using homogeneous ethylene / alpha-olefin copolymers in accordance with the present invention it is possible to obtain films with impact strengths substantially equal to, in some cases even better than, impact strengths of LLDPE-based films.

Example 6: Film 6

A co-extruded two-ply tubular tape is cast, which has a thickness of 9 mils, has a layer A that accounts for 85% or less of the tape thickness and a layer B that accounts for 15% or less of the tape thickness. Layer A comprises: (a) 50% by weight of a resin composition called ECD 103 linear homogeneous ethylene / hexene copolymer (hereinafter referred to as “linear homogeneous ethylene / alpha-olefin # 4”) obtained from Exxon Chemical Company; (b) ECD 106 linear homogeneous ethylene / hexene copolymer obtained from Exxon Chemical Company with a density of about 0.917 g / cc and a melt index of about 3 (hereinafter referred to as "linear homogeneous ethylene / alpha-olefin # 5"). ) 37% by weight; (c) 10% by weight LD 200.48 ^™ low density polyethylene, also obtained from Exxon Chemical Company with a density of 0.917 g / cc and a melt index of 6.7; And (d) a blend of 3% by weight of blocker # 1. In film 6, layer B consisted of EVA # 2 100% by weight.

The two-ply sheet was cooled to solid phase using a chill roll and then electronically crosslinked by irradiation in an amount of about 2-10MR using a 500Kev beam. The resulting crosslinked two-ply sheet was heated by hot air (210-220 ° F.), followed by stretching by about 300% longitudinal stretching and transverse stretching in the machine and transverse directions using a tenter frame, respectively. About 1 mil of biaxially stretched film was produced. The impact strength of the resulting film 6 is provided in Table IV below.

Example 7: Film 7

A co-extruded two-ply sheet is cast, which has a thickness of 18 mils, has an A layer, which occupies 85% or less of the sheet thickness, and a B layer, which occupies 15% or less of the sheet thickness. Layer A is (a) 97% by weight of linear homogeneous ethylene / alpha-olefin # 4; And (b) a blend of 3% by weight of blocker # 1. In film 7, layer B consisted of EVA # 2 100% by weight.

The two-ply sheet was cooled to solid phase using a chill roll and then electronically crosslinked by irradiation in an amount of about 2-10MR using a 500Kev beam. The resulting crosslinked two-ply sheet was heated by hot air (210-220 ° F.), followed by stretching by about 300% longitudinal stretching and transverse stretching in the machine and transverse directions, respectively, using a tenter frame to give a biaxial thickness of about 2 mils. A stretched film was produced.

Example 8: Film 8

A single layer of sheet is cast, the sheet being 18 mils thick (a) 97% by weight of linear homogeneous ethylene / alpha-olefin # 4; And (b) a blend of 3% by weight of blocker # 1. After the sheet was cast, the sheet was cooled to solid state using a cooling roll and then electronically crosslinked by irradiation in an amount of about 2 to 10 MR using a 500 Kev beam. The resulting crosslinked two-ply sheet was heated by hot air (210-220 ° F.) and then stretched about 300% in the longitudinal direction and about 300% in the transverse direction using a tenter frame to produce a biaxially stretched film of about 2 mils thick. Produced.

Example 9: Film 9

A single-ply tubular tape is cast, which is 27 mils thick and (a) 97% by weight of linear homogeneous ethylene / alpha-olefin # 4; And (b) a blend of 3% by weight of blocker # 1. After casting the tape, the tape was cooled to solid phase with cooling air or cooling water and then electronically crosslinked by irradiation in an amount of about 2 to 10 MR using a 500 Kev beam. The resulting crosslinked tape was heated by hot air (210-220 ° F.) and then stretched by about 300% longitudinal and transverse stretching in the machine and transverse directions, respectively, using the trapped bubble process to produce a biaxial thickness of about 3 mils. A stretched film is produced. The tubular film is then cut to form a flat film.

Example 10 Film 10

Film 10, layer A, (a) LLDPE # 1 67% by weight; (b) 30% by weight of Engage EG 8100 ^™ long chain branched homogeneous ethylene / alpha-olefin copolymer (hereinafter referred to as “homogeneous ethylene / alpha-olefin # 6”) obtained from The Dow Chemical Company; And (c) an antiblocking agent # 1 3% by weight of a blend, except that it was prepared by the same process used to produce film 6. In film 10, layer B consisted of EVA # 2 100% by weight. Further, as in film 6, in film 10, layer A occupies 85% or less of the tape thickness, and layer B occupies 15% or less of the tape thickness. The gauge impact of film 10 is provided in Table IV below.

Example 11: Film 11

Film 11, layer A is (a) 67% by weight of LLDPE # 1; (b) 30% by weight of Engage EG 8150 ^™ long chain branched homogeneous ethylene / alpha-olefin copolymer (hereinafter referred to as “homogeneous ethylene / alpha-olefin # 7”) obtained from The Dow Chemical Company; And (c) an antiblocking agent # 1 3% by weight of a blend, except that it was prepared by the same process used to produce film 6. In film 11, layer B consisted of EVA # 2 100% by weight. In addition, as in film 6, in film 11, layer A occupies 85% or less of the tape thickness, and layer B occupies 15% or less of the tape thickness. The instrument impact of film 11 is provided in Table IV below.

Example 12 Film 12

Film 12 was a resin called SLP 9042 linear homogeneous ethylene / alpha-olefin copolymer (hereinafter referred to as "linear homogeneous ethylene / alpha-olefin # 8"), in which layer A was obtained from (a) Exxon Chemical Company. weight%; (b) 47% by weight of LLDPE # 1; And (c) an antiblocking agent # 1 3% by weight of a blend, except that it was prepared by the same process used to produce film 6. In film 12, layer B consisted of EVA # 2 100% by weight. As in film 6, in film 12, layer A occupied 85% or less of the tape thickness, and layer B accounted for 15% or less of the tape thickness. Instrument impact of film 12 is provided in Table IV below.

Example 13: Film 13

Film 13 is film 6, except that layer A is 35% or less of film thickness, layer B is 50% or less of film thickness and layer C is a three-layer tubular film that is 15% or less of film thickness. It was prepared by the same process used to produce. Layer A was 94 weights of (a) Affinity HF 1031 ^™ long chain branched homogeneous ethylene / alpha-olefin (hereinafter referred to as “long chain branched homogeneous ethylene / alpha-olefin # 9”) obtained from The Dow Chemical Company. %; And (b) a blend of 6% by weight of Blocking Agent # 1. Layer B consisted of 100% by weight of Affinity HF 1570 ^™ long chain branched homogeneous ethylene / alpha-olefin (hereinafter referred to as “ethylene / alpha-olefin # 10”) obtained from The Dow Chemical Company. Layer C consisted of 100% by weight of EVA # 2. The gauge impact of film 13 is provided in Table IV below.

Example 14 Film 14

Film 14, layer A, (a) LLDPE # 1 67% by weight; (b) 30% by weight homogeneous ethylene / alpha-olefin # 7; And (c) 3% by weight of Blocker # 1 blend, except that it was prepared by the same process as used to produce film 13. Layer B consisted of 100% by weight homogeneous ethylene / alpha-olefin # 7 and layer C comprised 100% by weight of EVA # 2. The gauge impact of film 14 is provided in Table IV below.

Example 15 Film 15

Film 15 had an A layer comprising (a) 87 wt% of LLDPE # 1; (b) 10% by weight EVA # 1; And (c) an antiblocking agent # 1 3 wt% blend, except that it was a two-ply film made by the same process used to produce film 6. Layer B consisted of 100% by weight of EVA # 2. The instrument impact of film 15 is provided in Table IV below.

Film number Impact Strength (ℓb) 6 19 10 16 11 17 12 15 13 14 14 13 15 19

As can be seen from Table IV, the impact strengths of various examples of films suitable for use in the products of the present invention range from as little as about 13 pounds to as large as about 19 pounds.

Example 16: Film 16

Film 16 was made by a process similar to the process used to produce film 1. Film 16 was prepared by coextrusion of a tubular film having an A / B / C structure with a thickness ratio of 15/70/15. Layer A is (a) 87 wt% LLDPE # 1; (b) 10% by weight EVA # 1; And (c) an outer layer consisting of 3% by weight of blocker # 1. Layer B comprises (a) 97% by weight of homogeneous ethylene / alpha-olefin copolymer # 10; And (b) 3% by weight of blocker # 1. Layer C was an inner layer consisting of 100% by weight of EVA # 2.

A co-extruded three-ply tubular tape was cast, which was 20 mils thick. The 2-ply tube was cooled to solid in the water bath and then electronically crosslinked by irradiation in an amount of about 12MR using a 500Kev beam.

The resulting crosslinked two-ply tube was heated by immersion in a high temperature water bath of about 210 ° F., followed by about 370% longitudinal and transverse stretching in the machine and transverse directions, respectively, using trapped air bubbles received between the two nip rolls. As a result of stretching, a three-ply film having a thickness of about 1.46 mils in the form of a tube was produced.

After longitudinal stretching, when the resulting hot water-shrinkable flat film tube passed through a pair of nip rolls, the inner C layer bonded to itself when the tube was pressed, resulting in a six-ply film about 2.9 mils thick. Film 16 was determined to have a free shrinkage of about 48% at 185 ° F. (determined using ASTM 2732), and an instrument impact of film 16 (determined using ASTM D 3763) was determined to be about 110 pounds. .

Example 17 Film 17

Film 17 was made by a process similar to the process used to produce film 16. Film 17 was produced by coextrusion of a tubular film having an A / B / C structure with a thickness ratio of 30/50/15. Layer A is (a) 87 wt% LLDPE # 1; (b) 10% by weight EVA # 1; And (c) an outer layer consisting of 3% by weight of blocker # 1. Layer B comprises (a) 97% by weight of long chain branched homogeneous ethylene / alpha-olefin copolymer # 3; And (b) 3% by weight of blocker # 1. Layer C was an inner layer consisting of 100% by weight of EVA # 2. A co-extruded three-ply tubular tape was cast, which was 20 mils thick. The two-ply tube was cooled to solid in a water bath and then electronically crosslinked by irradiation in an amount of about 2-10MR using a 500Kev beam.

The resulting crosslinked two-ply tube was heated by immersion in a high temperature water bath of about 208 ° F., followed by about 340% longitudinal stretching in the machine direction and about 370% in the transverse direction using the trapped air bubbles contained between the two nip rolls. As a result of stretching by lateral stretching, a three-ply film about 1.6 mils in thickness in the form of a tube was produced.

After longitudinal stretching, when the resulting hot water-shrinkable flat film tube passed through a pair of nip rolls, the inner C layer bonded to itself when the tube was pressed, resulting in a six-ply film about 3.2 mils thick. Film 17 was determined to have a free shrinkage at 185 ° F. (determined using ASTM 2732) of about 57%, and the instrument impact of film 16 (determined using ASTM D 3763) was approximately 63 pounds. . Film 17 is thought to be significantly better when drawn at a temperature of about 195 ° F., as the homogeneous polymer has a density of 0.9016 g / cc, which allows for a lower draw temperature.

Example 18 Film 18

Film 18 was produced by a process similar to the process used to produce films 16 and 17. Film 18 was prepared by coextrusion of a tubular film having an A / B / C structure with a thickness ratio of 15/70/15. Layer A is (a) 87 wt% LLDPE # 1; (b) 10% by weight EVA # 1; And (c) an outer layer consisting of 3% by weight of blocker # 1. The B layer had the same chemical composition as the A layer. Layer C was an inner layer consisting of 100% by weight of EVA # 2. A co-extruded three-ply tubular tape was cast, which was 20 mils thick. The 2-ply tube was cooled to solid in the water bath and then electronically crosslinked by irradiation in an amount of about 2-10MR using a 500Kev beam.

The resulting crosslinked two-ply tube was heated by immersion in a high temperature water bath of about 210 ° F., followed by about 360% longitudinal stretching in the machine direction and about 370% in the transverse direction using the trapped air bubbles contained between the two nip rolls. As a result of stretching by lateral stretching, a three-ply film having a thickness of about 1.5 mils in the form of a tube was produced.

After longitudinal stretching, when the resulting hot water-shrinkable flat film passed through a pair of nip rolls, the inner C layer bonded to itself when the tube was pressed, resulting in a six-ply film about 3.0 mils thick. Film 18 was determined to have a free shrinkage at 185 ° F. (determined using ASTM 2732) of about 50%, and an instrument impact of film 18 (determined using ASTM D 3763) was about 100 pounds. .

Example 19 Film 19

A co-extruded seven-ply tubular tape was cast, with a thickness of 18.6 mils, having layer A, which occupies 85% or less of the tape thickness, and layer B, which occupies 15% or less of the tape thickness. The 3-ply tube was cooled to solid phase in a water bath and then electronically crosslinked by irradiation in an amount of about 2-10MR using a 500Kev beam. The resulting crosslinked three-ply tube was extrusion coated with four additional polymer layers extruded through the annular die in the process shown in FIG. 6. The resulting 26.5 mil extruded coated tape is then immersed in a high temperature water bath of about 192 ° F., followed by about 300% longitudinal stretching in the machine direction and about 325 in the transverse direction using the trapped air bubbles contained between the two nip rolls. Stretching was performed by% lateral stretching. The stretching resulted in a two-ply film of about 2.7 mils in the form of a tube. Table V below shows the function of each layer in the film along with the chemical composition and thickness of each layer:

Floor number Floor location / function Chemical composition of layers Layer thickness (mils) 202 Inner layer / sealing layer EVA # 3 90% LLDPE # 1 10% 0.36 204 Inner layer / bulk layer Homogeneous Ethylene / Alpha-olefin Copolymer # 11 1.39 206 Inner layer / Tie layer EVA # 4 100% 0.15 208 Inner layer / O ₂ -blocker PVDC Blend # 1 0.18 210 Inner layer / Tie layer EVA # 4 100% 0.15 212 Inner layer / bulk layer Homogeneous Ethylene / Alpha-olefin Copolymer # 1 0.30 214 Outer layer / protective layer EVA # 5 92.5% LLDPE # 1 7.5% 0.17

EVA # 3 is a PE 3507-2 ^™ ethylene / vinyl acetate copolymer with a 6.2% vinyl acetate content, a melt index of 2.5 and a density of 0.93 g / cc, obtained from DuPont. EVA # 4 is an EP 4062-2 ^™ ethylene / vinyl acetate copolymer having a vinyl acetate content of 15%, a melt index of 2.5 and a density of 0.938 g / cc, also obtained from DuPont. EVA # 5 is an LD-318.92 ^™ ethylene / vinyl acetate copolymer having a vinyl acetate content of 9%, a melt index of 2.0 and a density of 0.93 g / cc, obtained from Exxon. PVDC Blend # 1 comprises: (a) about 96% Dow MA134 ^™ vinylidene chloride / methyl acrylate copolymer having a methyl acrylate content of 8.5% from The Dow Chemical Company, Midland, Michigan; (b) about 2% PLAS CHEK 775 ^™ epoxidized soybean oil obtained from Ferro Chemicals, Bedford, Ohio; And (c) about 2% by weight of a METABLEN L1000 ^™ acrylate blend obtained from Elf Atochem, Philadelphia, PA. Methyleneble L1000 comprises about 53 weight percent methyl methacrylate ("MMA"), 29 weight percent butyl methacrylate ("BMA") and 19 weight percent butyl acrylate ("BA").

Free shrinkage at 185 ° F. (ASTM) for film 19 consisting of two films, each film being about 2.7 mils thick (ie, a total thickness of about 5.4 mils) and each film consisting of the seven layers described above (ASTM Determined using 2732), the instrument impact was about 112 lb _f and the energy required to break was about 5 ft · lb.

Example 20 Film 20

Film 20, layer A, (a) 95.5% by weight of LLDPE # 1; And (b) 4.5 weight percent block protection masterbatch, similar to Blocker # 1, commercially available as the TekNOR 10183ACP ^™ Blocker, available from the Techner Apex Plastics Division, Porterett, Rhode Island. ESCORENE® LD with a blend of 28% vinyl acetate, 0.950 g.cc density and 5.7 melt index, consisting of a blend and obtained from Exxon Chemical Company, Houston, Texas Prepared by a process similar to the process used to produce film 3, except that it consisted of 100% by weight of -761.36 ^™ ethylene / vinyl acetate copolymer. In addition, as in film 3, in film 20, layer A occupied 85% or less of the tape thickness, and layer B accounted for 15% or less of the tape thickness. Film 20 was sealed as described above in film 3, the seal strength of the resulting seal was tested, and the parallel plate burst strength of the resulting side seal was tested. The results of these tests are described in Table II above.

Comparison of Films 3 and 20 with Comparative Example 21

Other tests were made by fabricating the side seal bags, this time using a butt rod sealer modified to simulate a bag with a condition of 0.0937 inches of radial wire (instead of the 1/4 inch ribbon described above) and a pressure of about 50 psi. The heating time of about 0.9 seconds followed by the cooling time of 0.3 seconds, the potential of the current through the heated wire was 38 volts. The resulting bag was placed between parallel walls about 3-4 inches apart (ie, "parallel rupture test") and then the bag was inflated until one of the side seals was damaged. As in the drop test results presented above, damage always occurred in the region adjacent the seal. The seal was not damaged. The pressure inside the bag at the time of injury was a measure of strength. Bags made from the film according to Example 3 had an average burst strength of 522 inches of water in the parallel plate rupture test, and the strength was almost constant (i.e., a range from about 430 inches of water to about 640 inches of water). . In contrast, the smaller, non-crosslaminated film exhibited a lower parallel plate burst strength, for example, about 100 to 150 inches of water, compared to a film of about 2 mils in total thickness.

In the product according to the invention, preferably the total thickness of the raw film from which the bag is formed is about 1.5 to 5 mils, more preferably about 2.5 mils. The raw film on which the bag is formed may be a single layer film, but preferably the raw film on which the bag is formed is a multilayer film of 3 to 7 layers, preferably 4 layers.

The polymer components used to make the films useful in the products according to the invention may also contain appropriate amounts of other additives generally included in such compositions. These additives include additives known to those skilled in the art of slip agents (eg talc), antioxidants, fillers, dyes, pigments, radiation stabilizers, antistatic agents, elastomers and packaging films.

The films used to make the articles of the invention are preferably not only irradiated to induce crosslinking, but also corona treated to roughen the surfaces of the films to be bonded to one another. In the irradiation process, the film is subjected to a strong radiation treatment such as corona discharge, plasma, flame, ultraviolet, X-ray, gamma ray, beta-ray and high energy electron treatment to induce crosslinking between molecules of the substance to be irradiated. Methods of investigating polymeric films are disclosed in US Pat. No. 4,064,296 to Bornstein et al., Incorporated herein by reference. Vonstein et al. Disclose the use of ionizing wire to crosslink polymers present in a film.

To cause crosslinking, high energy electrons of suitable radiation dose are applied to the film. Preferably, the irradiation is carried out by an electron accelerator and the dose is determined by standard dosimeter methods. Other accelerators such as Vander Graff or resonant transformers can also be used. The radiation is not limited to electrons from the accelerator because any ionizing wire can be used. The ionizing wire crosslinks the polymer in the film. Preferably, the film is irradiated with a radiation dose of 2 to 15 MR, more preferably 2 to 10 MR. As can be seen from the description of preferred films for use in the present invention, the most preferred radiation dose depends on the film and its end use.

Corona treatment of the film is performed by applying the film surface to corona discharge, i.e. by ionizing a gas such as air close to the film surface and causing oxidation and other changes (e.g., roughening the surface) of the film surface. It is initiated by a high voltage passing through adjacent electrodes. Methods of corona treatment of polymeric materials are disclosed in US Pat. No. 4.120,716, issued October 17, 1978 to Bonnet, which is incorporated herein by reference, which discloses corona for oxidizing polyethylene surfaces. It is disclosed to improve the bonding characteristics of the polyethylene surface by treatment. US Patent No. 4,879,430, issued to Hoffman, incorporated herein by reference, discloses the use of corona discharge for the treatment of meat cook-in packaging plastic webs. Corona treatment increased the adhesion of meat to protein material. Corona treatment is a preferred treatment method for the multilayer film used to make the bag of the present invention, but a plasma treatment method for the film may also be used.

In general, the sealing of the film to produce the bag uses nichrome wire fixed to a hot rod (sealing) or a cold metal rod (impact seal), as known to those skilled in the art, or ultrasonic waves, high frequency radiation, and lasers. It may be carried out using any other means known to those skilled in the art. Preferred sealing means is an impact sealer. Films that are predominantly polyethylene are generally sealed using impact sealing or hot rod sealing. As is known to those skilled in the art, both linear and molded seals can be achieved. In general, the sealing and cutting of the tubes to produce the bags are filed in US Pat. Nos. 3,552,090, US Pat. Nos. 3,383,746 and July 25, 1969 to Owen, which is incorporated herein by reference. US Patent Application No. 844,883.

The products of the present invention are useful in a wide range of packaging applications, such as in the field of construction, among a wide range of fields, such as agriculture, industrial nonfood, industrial overlap films, medicine, retail, food packaging, household, industrial, and other applications. More specifically, the products of the present invention are tools and hardware (for civil and military), machinery parts, instruments, marine hardware (e.g. anchors, props, etc.), corrosive metal products, industrial parts containing rust inhibitors, powdered chemistry Pharmaceuticals and concentrates (especially bulk chemically packaged photographic chemicals), industrial cartridge packs, bricks (especially refractory bricks), toys, bearings, dried pet foods, mainly buckets, especially heavy five-gallon buckets , Non-assembled wood products cut to specification, mainly packed in woven bags, products requiring packaging as a practical barrier against atmospheric oxygen, coffee, hops, shrimp, peanuts, raisins, postal parcels, heat resistant pouches, Viscous fluids, explosives, frozen products, ballistic cargo, textiles (ready-made and household clothing), furniture, products dangerous to children (i.e. flexible packaging that children cannot play), fertilizers and grains (especially overseas Cargoes), plants (especially potted plants), insecticides and other toxic and harmful chemicals, insect repellents, sand bags for flood control, water, seeds, skis, antiques and art, firewood, lumber, tires, Paper and plastic film and sheet products (especially 10 to 100 pound rolls, especially when the multilayer film has a layer of carbon black embedded (ie blended with polymer) to prevent paper and / or film from exposure to light) Units of photo paper and photographic films), occult blood specimens, pouches that are not playable for children, and packaging (ie, multipacks) containing multiple products.

The product according to the invention can also be used for the packaging of fresh meat products comprising bones. Among them, poultry, pork, beef, lamb, goat meat, horse meat and fish can be packaged in the product according to the invention. More specifically, preferred meat products to be packaged in the product of the present invention include ham, pork ribs, pork chops, dorsal ribs, short beef loin, short ribs, turkey meat and pork loin. The product of the present invention is particularly useful for packaging a pair of bones of the entire pork loin.

In addition, the products of the present invention also provide protection of mobile homes (particularly shrinkable) as liners, pools, etc. for landfills in compressed packaging, as marine personal safety devices such as boat tarps (particularly shrinkable). As a tag / label in the case of temporary shields, tents, greenhouse covers, as a viewing application (especially as a plastic grid system), as a shrinking overlap for furniture edges, and as a vacuum-press bag (e.g. vacuum As bag veneer presses, as slit fences, for packaging and roofing applications, as automatic substrates in bag handles, as beverage carriers, as oil leak containment films in raincoats, as dispensers (e.g. For example, for adhesives such as epoxy), as horizontal silos, as solar panel covers to be combined with corrugated materials, as anti-theft packaging, travel portables, military bag bags, etc. For pallet banding in packaging, as a non-adhesive shrink bag, as a shrinkable mattress cover, as a dust cover (especially for a car), as a proof bag, as a dry bag, as a dry bag, in trays in industrial surface packaging ( As a shrinkable film for tray packs (especially cans), as a rubber sheet cured wrap-release sheet, as a cloth covering the stage (for painting, tents, etc.), reproducible for photographic plates, films, etc. As an envelope or pouch, as a substitute for papang packaging materials, as a recreational device for sliding in ice, snow, etc., as a rollstock overlap (for aluminum beverage cans, paper, etc.), for medical intravenous use As a bag, as a shrinking balloon in a shrinking bag for packaging and storage (especially for heavy items such as books, plates, etc.), it is accepted by Hassan, Travel, and Hurley, Jr. For use in the protective device disclosed in U.S. Patent No. 5,568,902, as a pouch for children to play with, for children to play with pouches for air bags in a wide range of medical applications, such as For example, for spiral wraps, underground pipes and tight shrinks, etc., for use as a tape (if coated with adhesive), for compression devices (hemostats, splints, etc.), as reinforcements (e.g. For example, for concrete, fiberglass, etc., as cable components, as straight jackets, as euthanasia chambers, as handcuffs and other restraints and fasteners, as bodies for transport, tanks (e.g., fuel tanks, solvent tanks, etc.) ), In pipes, as ostomy or colostomy pouches or bags, pouches, etc., as sails on water slides, at target, as emergency runways for planes, as hill travers On runways for hill traversing, on fabrics (especially slits, weaves), on ropes for high tension applications, as components for road construction, as component bearings in mailboxes, as carpet bearings, as shields, as conveyors Useful as belts or sheets and in tanning.

While the present invention has been described with reference to preferred embodiments, those skilled in the art will readily appreciate that modifications and variations may be made without departing from the principles and scope of the invention. Accordingly, such modifications may be made within the scope of the following claims.

Claims (25)

A film that is not cross-laminate, Uncrosslinked films are linear low density polyethylene, high density polyethylene, homogeneous ethylene / alpha-olefin copolymers, polycarbonates, polyester homopolymers, polyamides, ethylene / acid copolymers, ethylene / ester copolymers, ethylene / vinyl acetate aerials At least one selected from the group consisting of copolymers, ionomers, ethylene / carbon monoxide, very low density polyethylene, low density polyethylene, polyolefins, ethylene / propylene copolymers, ethylene / norbornene copolymers and ethylene / styrene copolymers; , Uncrosslinked film is sealed in itself or linear low density polyethylene, high density polyethylene, homogeneous ethylene / alpha-olefin copolymers, polycarbonates, polyesters, polyamides, ethylene / acid copolymers, ethylene / ester copolymers, ethylene / Vinyl acetate copolymers, ionomers, ethylene / carbon monoxide, very low density polyethylene, low density polyethylene, polyolefins, ethylene / propylene copolymers, ethylene / propylene / diene terpolymers, ethylene / norbornene copolymers and ethylene / styrene air Sealed in a second film comprising at least one selected from the group consisting of coalescing, Products with a parallel plate burst strength of at least 300 inches of water. The method of claim 1, The product has a total thickness of about 3 to 20 mils and the parallel plate burst strength of the product is about 300 to 2000 inches of water. The method of claim 2, A product in which the film is a single layer film. The method of claim 2, Film, (A) at least one selected from the group consisting of ethylene / vinyl ester copolymers, ethylene / vinyl acid copolymers, ionomers and homogeneous ethylene / alpha-olefin copolymers having a density of about 0.87 to 0.91 g / cc. A first inner layer and a second inner layer; And (B) (a) linear low density polyethylene, high density polyethylene, low density polyethylene, very low density polyethylene, homogeneous ethylene / alpha-olefin copolymers, olefin homopolymers, polycarbonates, polyamides, ethylene / acid copolymers, ethylene / esters At least one selected from the group consisting of copolymers, ester homopolymers, ionomers, ethylene / carbon monoxide copolymers, ethylene / propylene / diene terpolymers, ethylene / norbornene copolymers and ethylene / styrene copolymers, and (b) A first outer layer comprising at least one selected from the group consisting of ethylene / vinyl ester copolymers, ethylene / vinyl acid copolymers, ionomers and homogeneous ethylene / alpha-olefin copolymers having a density of about 0.87 to 0.91 g / cc; Second outer layer Wherein the at least one layer selected from the group consisting of a first outer layer and a second outer layer is a multilayer film sealed to itself or sealed to another outer layer. The method of claim 4, wherein The total thickness of the multilayer film is about 3 to 7 mils and the parallel plate burst strength of the product is about 300 to 1000 inches of water. The method of claim 5, The total thickness of the multilayer film is about 4 to 5 mils, and the parallel plate burst strength of the product is about 400 to 700 inches of water. The method of claim 4, wherein Multi-layer film is heat shrinkable. The method of claim 7, wherein The multilayer film is biaxially stretched and the free shrinkage at 185 ° F. is about 10-100%. The method of claim 4, wherein The multilayer film further comprises an O ₂ -blocking layer comprising at least one selected from the group consisting of ethylene / vinyl alcohol copolymers, polyvinyl chlorides, polyvinylidene chlorides, polyamides, polyesters and polyacrylonitriles. Product. The method of claim 1, An article in which the film is irradiated with a radiation dose of about 50 to 150 kilolograys (kGy). The method of claim 1, An article comprising at least one selected from the group consisting of end-seal bags, side-seal bags, L-shaped seal bags, pouches, and backseamed cases. (A) linear low density polyethylene, high density polyethylene, low density polyethylene, very low density polyethylene, homogeneous ethylene / alpha-olefin copolymers, olefin homopolymers, polycarbonates, polyamides, ethylene / acid copolymers, ethylene / ester copolymers, A first multilayer film comprising at least one selected from the group consisting of ester homopolymers, ionomers, ethylene / carbon monoxide copolymers, ethylene / propylene / diene terpolymers, ethylene / norbornene copolymers and ethylene / styrene copolymers; And (B) linear low density polyethylene, high density polyethylene, low density polyethylene, very low density polyethylene, homogeneous ethylene / alpha-olefin copolymers, olefin homopolymers, polycarbonates, polyamides, ethylene / acid copolymers, ethylene / ester copolymers, Second multilayer film comprising one or more selected from the group consisting of ester homopolymers, ionomers, ethylene / carbon monoxide copolymers, ethylene / propylene / diene terpolymers, ethylene / norbornene copolymers and ethylene / styrene copolymers Including; The first multilayer film is not a crosslaminated film, the second multilayer film is also not a crosslaminated film, the first multilayer film is sealed to the second multilayer film, and the thickness of the first multilayer film is about 3 to 20 mils And the second multilayer film has a thickness of about 3 to 20 mils and the parallel plate burst strength of the product is about 300 to 2000 inches of water. The method of claim 12, (A) In the group consisting of (i) an ethylene / vinyl ester copolymer, an ethylene / vinyl acid copolymer, an ionomer and a homogeneous ethylene / alpha-olefin copolymer having a density of about 0.87 to 0.91 g / cc A first inner layer and a second inner layer comprising at least one selected; And (ii) (a) linear low density polyethylene, high density polyethylene, low density polyethylene, very low density polyethylene, homogeneous ethylene / alpha-olefin copolymers, olefin homopolymers, polycarbonates, polyamides, ethylene / acid copolymers, ethylene / At least one selected from the group consisting of ester copolymers, ester homopolymers, ionomers, ethylene / carbon monoxide copolymers, ethylene / propylene / diene terpolymers, ethylene / norbornene copolymers and ethylene / styrene copolymers, and (b A first outer layer comprising at least one selected from the group consisting of ethylene / vinyl ester copolymers, ethylene / vinyl acid copolymers, ionomers and homogeneous ethylene / alpha-olefin copolymers having a density of about 0.87 to 0.91 g / cc And a second outer layer; (B) in the group consisting of (i) an ethylene / vinyl ester copolymer, an ethylene / vinyl acid copolymer, an ionomer and a homogeneous ethylene / alpha-olefin copolymer having a density of about 0.87 to 0.91 g / cc A first inner layer and a second inner layer comprising at least one selected; And (ii) (a) linear low density polyethylene, high density polyethylene, low density polyethylene, very low density polyethylene, homogeneous ethylene / alpha-olefin copolymers, olefin homopolymers, polycarbonates, polyamides, ethylene / acid copolymers, ethylene / At least one selected from the group consisting of ester copolymers, ester homopolymers, ionomers, ethylene / carbon monoxide copolymers, ethylene / propylene / diene terpolymers, ethylene / norbornene copolymers and ethylene / styrene copolymers, and (b A first outer layer comprising at least one selected from the group consisting of ethylene / vinyl ester copolymers, ethylene / vinyl acid copolymers, ionomers and homogeneous ethylene / alpha-olefin copolymers having a density of about 0.87 to 0.91 g / cc And a second outer layer; The at least one layer selected from the group consisting of the first outer layer of the first multilayer film and the second outer layer of the first multilayer film, the group consisting of the first outer layer of the second multilayer film and the second outer layer of the second multilayer film A product that is sealed to one or more layers selected from. The method of claim 13, The total thickness of the first multilayer film is about 3-7 mils, the total thickness of the second multilayer film is about 3-7 mils, and the parallel plate burst strength of the article is about 300-1000 inches of water. The method of claim 14, The two outer layers of the first multilayer film are substantially the same in chemical composition and thickness; The two inner layers of the first multilayer film are substantially the same in chemical composition and thickness; The two outer layers of the second multilayer film are substantially the same in chemical composition and thickness; An article having substantially the same thickness as the chemical composition of the two inner layers of the second multilayer film. The method of claim 13, An article having substantially the same chemical composition and thickness as the second multilayer film. The method of claim 16, The two outer layers of the first multilayer film are substantially the same in chemical composition and thickness; The two inner layers of the first multilayer film are substantially the same in chemical composition and thickness; The two outer layers of the second multilayer film are substantially the same in chemical composition and thickness; An article having substantially the same thickness as the chemical composition of the two inner layers of the second multilayer film. The method of claim 13, A product comprising at least one member selected from the group consisting of a butt-sealed back seamed case having a pouch and a butt-seal tape. The method of claim 13, The first multilayer film further comprises an O ₂ -blocking layer comprising at least one member selected from the group consisting of ethylene / vinyl alcohol copolymers, polyvinyl chlorides, polyvinylidene chlorides, polyamides, polyesters and polyacrylonitriles. Including; The second multilayer film further comprises an O ₂ -blocking layer comprising at least one member selected from the group consisting of ethylene / vinyl alcohol copolymers, polyvinyl chloride, polyvinylidene chloride, polyamide, polyester and polyacrylonitrile Containing products. The method of claim 19, A product of which the chemical composition of the O ₂ -blocking layer of the first multilayer film is the same as that of the second multilayer film. The method of claim 13, Multi-layer film is heat shrinkable. The method of claim 21, The multilayer film is biaxially stretched and the free shrinkage at 185 ° F. is about 10-100%. The method of claim 13, An article in which the film is irradiated with a radiation dose of about 50 to 150 kGy. Includes packaging and products wrapped in packaging, (A) Packaging material is linear low density polyethylene, high density polyethylene, homogeneous ethylene / alpha-olefin copolymer, polycarbonate, polyester homopolymer, polyamide, ethylene / acid copolymer, ethylene / ester copolymer, ethylene / vinyl acetate copolymer Crosses comprising at least one selected from the group consisting of ionomers, ethylene / carbon monoxide, very low density polyethylene, low density polyethylene, polyolefins, ethylene / propylene copolymers, ethylene / norbornene copolymers and ethylene / styrene copolymers An unlaminated film, the uncrosslaminated film being sealed on itself, or a linear low density polyethylene, high density polyethylene, homogeneous ethylene / alpha-olefin copolymer, polycarbonate, polyester, polyamide, ethylene / acid copolymer , Ethylene / ester copolymer, on Ethylene / vinyl acetate copolymers, ionomers, ethylene / carbon monoxide, very low density polyethylene, low density polyethylene, polyolefins, ethylene / propylene copolymers, ethylene / propylene / diene terpolymers, ethylene / norbornene copolymers and ethylene / styrene Sealed in a second film comprising at least one member selected from the group consisting of copolymers; (B) The product contains tools, hardware, military parts, instruments, marine hardware, corrosive metal products, industrial parts containing antirust agents, aerosol spray cans, waxes, powdered chemicals, liquid chemical concentrates, industrial cartridge packs. (cartridge pack), toys, bearings, bricks, dried pet food, adhesives, caulks, plaster mixes, pre-assembled non-assembled wooden products, coffee, hops, shrimp , Peanuts, heat resistant pouches, viscous fluids, explosives, frozen products, ballistic cargo, textiles, furniture, cars, boats, dangerous goods for children, fertilizers and grains, plants, pesticides, sand bags for flood control, water, seeds, skiing A packaged product comprising at least one selected from the group consisting of art, art, unground wood (especially firewood), lumber, tires and occult blood specimens. The method of claim 24, Packaged product with multiple products in the packaging.